Lithuanian
3.400.000 speakers
18 language specific characters
ISO 639 code: lit
Lithuanian is a Baltic language related to Latvian and Old Prussian with about 3.4 million speakers in Lithuania. There are also Lithuanian speakers in Poland, the USA, Brazil, Argentina, Canada, the UK and Uruguay.
Lithuanian is considered to oldest surviving Indo-European language and is thought to have retained some features of Proto-Indo-European (PIE) such as pitch-accent and a complex inflexional case system. Some words in Lithuanian even resemble words in Sanskrit and Latin.
source
wikipedia.org, omniglot.com, evertype.com & ethnologue.comsample text